System-in-a-package based flash memory card

ABSTRACT

A system-in-a-package based flash memory card including an integrated circuit package occupying a small overall area within the card and cut to conform to the shape of a lid for the card. An integrated circuit may be cut from a panel into a shape that fits within and conforms to the shape of lids for a finished memory card, such as for example an SD Card. The integrated circuit package may be a system-in-a-package, a multi-chip module, or other arrangement where a complete electronic system is formed in a single package.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention is related to the following U.S. patentapplications:

U.S. Design patent application Ser. No. 29/230,382, entitled “SIP BasedFlash Memory Card,” by Takiar et al., filed concurrently herewith;

U.S. Design patent application Ser. No. 29/230,385, entitled“Translucent Flash Memory Card,” by Day et al., filed concurrentlyherewith; and

U.S. Utility patent application Ser. No. 11/129,637, entitled “Method OfAssembling Semiconductor Devices With LEDs,” by Takiar et al., filed May13, 2005.

Each of the above-identified patent applications is incorporated byreference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate to a system-in-a-packagebased flash memory card including an integrated circuit packageoccupying a small overall area within the card and cut to conform to theshape of a lid for the card.

2. Description of the Related Art

The strong growth in demand for portable consumer electronics is drivingthe need for high-capacity storage devices. Non-volatile semiconductormemory devices, such as flash memory storage cards, are becoming widelyused to meet the ever-growing demands on digital information storage andexchange. Their portability, versatility and rugged design, along withtheir high reliability and large capacity, have made such memory devicesideal for use in a wide variety of electronic devices.

One exemplary standard for flash memory cards is the so-called SD flashmemory card. The SD (Secure Digital) Card is a secure flash memory aboutthe size of a postage stamp. Jointly developed by SanDisk, Toshiba andMatsushita Electronic (which makes Panasonic products), the SD Cardweighs approximately two grams and is used for memory storage in a widevariety of digital products, including for example digital musicplayers, cellular phones, handheld PCs (HPCs), digital cameras, digitalvideo camcorders, smart phones, car navigation systems and electronicbooks.

In the past, electronic devices such as SD cards have included anintegrated circuit (“IC”) system consisting of several individuallypackaged ICs each handling different functions, including logic circuitsfor information processing, memory for storing information, and I/Ocircuits for information exchange with the outside world. Theindividually packaged ICs have been mounted separately on a substratesuch as a printed circuit board to form the IC system. In conventionalSD Cards including individually packaged components on a printed circuitboard, the printed circuit board took up all or almost all of theavailable space within the card. The printed circuit board was formed tothat size in order to contain all of the individually packagedcomponents.

More recently, system-in-a-package (“SiP”) and multichip modules (“MCM”)have been developed where a plurality of integrated circuit componentshave been packaged together to provide a complete electronic system in asingle package. Typically, an MCM includes a plurality of chips mountedside by side on a substrate and then packaged. An SiP typically includesa plurality of chips, some or all of which may be stacked on a substrateand then packaged.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to a system-in-a-packagebased flash memory card including an integrated circuit (“IC”) packageoccupying a small overall area within the card and cut to conform to theshape of a lid for the card. An integrated circuit may be cut from apanel into a shape that fits within and conforms to the shape of lidsfor a finished memory card, such as for example an SD Card. Theintegrated circuit package may be a system-in-a-package, a multi-chipmodule, or other arrangement where a complete electronic system isformed in a single package.

In embodiments, the IC package is cut with a chamfer that matches upwith and conforms to the size and shape of a chamfer formed in a lid foran SD flash memory card. Similarly, the IC package is also cut with anotch that is sized and positioned so as to define a space in which aread/write switch in the SD flash memory card may operate. Moreover,forming all of the IC components within an SiP or similar packageprovides a significant savings of space within the finished flash memorycard in comparison to conventional printed circuit boards includingindividually packaged components. Whereas the printed circuit board withindividually packaged components took up all or substantially all of theavailable space within a standard SD Card, the IC package takes up lessthan one-half of the available space in the flash memory card of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of the method of fabricating a flash memory cardaccording to embodiments of the present invention.

FIG. 2 is a top view of a panel of integrated circuits during thefabrication process according to the present invention.

FIG. 3 is a cross-sectional view through line 3-3 in FIG. 2.

FIG. 4 is a top view of a panel of molded integrated circuits accordingto embodiments of the present invention prior to being cut intoindividual integrated circuit packages.

FIG. 5 is an enlarged view of a pair of integrated circuits with theinternal components and cut lines shown.

FIG. 6 is a top view of an integrated circuit package according toembodiments of the present invention.

FIG. 7 is an edge view of a first edge of the integrated circuit packageaccording to embodiments of the present invention.

FIG. 8 is an edge view of a second edge of the integrated circuitpackage according to embodiments of the present invention.

FIG. 9 is an edge view of a third edge of the integrated circuit packageaccording to embodiments of the present invention.

FIG. 10 is an edge view of a fourth edge of the integrated circuitpackage according to embodiments of the present invention.

FIG. 11 is a bottom view of an integrated circuit package according toembodiments of the present invention.

FIG. 12 is a perspective view of a flash memory card including theintegrated circuit package of FIG. 6 mounted in a top and bottom lid.

FIG. 13 is a top view of a flash memory card including the integratedcircuit package of FIG. 6 mounted in a top and bottom lid.

FIG. 14 is a bottom view of a flash memory card including the integratedcircuit package of FIG. 6 mounted in a top and bottom lid.

DETAILED DESCRIPTION

Embodiments of the invention will now be described with reference toFIGS. 1 through 14 which relate to a system-in-a-package based flashmemory card including an integrated circuit package fitting within thefootprint of a lid for the package. It is understood that the presentinvention may be embodied in many different forms and should not beconstrued as being limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete and will fully convey the invention to those skilled in theart. Indeed, the invention is intended to cover alternatives,modifications and equivalents of these embodiments, which are includedwithin the scope and spirit of the invention as defined by the appendedclaims. Furthermore, in the following detailed description of thepresent invention, numerous specific details are set forth in order toprovide a thorough understanding of the present invention. However, itwill be clear to those of ordinary skill in the art that the presentinvention may be practiced without such specific details.

A method for forming a flash memory card according to embodiments of thepresent invention will now be described with reference to the flowchartof FIG. 1. The fabrication process begins in step 50 with a panel 100(FIGS. 2 and 3). The type of panel 100 used in the present invention isnot critical and may for example be a substrate in the form of a printedcircuit board (“PCB”), a lead frame, a tab automated bonding (“TAB”)tape or other known base on which integrated circuits may be assembledand encapsulated. In an embodiment, panel 100 may be a PCB substrateformed of a dielectric core having a conductive layer formed on the topand/or bottom surface of the core. In step 52, a conductance pattern maybe formed on one or both conductive layers of panel 100 to establish anelectrical connection between the components mounted on panel 100. Theconductance pattern may further include contact pads, lead fingers orother external connectors for electrical connection between theintegrated circuit components and external electronic devices.

A plurality of discrete integrated circuits 102 may be batch processedon panel 100 to achieve economies of scale. Each of these integratedcircuits 102 may then be encapsulated and singulated to form a pluralityof integrated circuit packages as explained hereinafter. Each integratedcircuit 102 being formed on panel 100 may include one or more passivecomponents 104 surface mounted to panel 100 in step 54. The type andnumber of passive components 104 is not critical to the presentinvention and may vary widely in alternative embodiments. In anembodiment, the passive components 104 may include capacitors and/orresistors physically and electrically coupled to panel 100 as is knownin the art.

Embodiments of the present invention may further include a lightemitting diode (“LED”) 108 surface mounted to panel 100 in a step 56.The LED 108 may be embedded within the finished package and have anactive end emitting light out of an edge of the finished package. Apackage including such an LED is described in U.S. Utility patentapplication Ser. No. 11/129,637, entitled “Method Of AssemblingSemiconductor Devices With LEDs,” by Takiar et al., filed May 13, 2005,which application has been incorporated by reference herein in itsentirety. LED 108 may be omitted in embodiments of the invention.

Each integrated circuit 102 may further include one or moresemiconductor die 114 mounted to panel 100 in step 58 in a knownadhesive or eutectic die bond process, using a known die-attachcompound. The number and type of semiconductor die 114 may vary greatlyin alternative embodiments of the invention. In one embodiment, the oneor more die 114 may include a flash memory array (e.g., NOR, NAND orother), S-RAM or DDT, and/or a controller chip such as an ASIC. Othersemiconductor die are contemplated. The one or more die 114 may beelectrically connected to panel 100 by wire bonds 116 in step 60 in aknown wire-bond process.

While the mounting of the passive components, the LED and thesemiconductor die are disclosed as separate steps in the flowchart ofFIG. 1, it is understood that these steps may be performed in differentorders, and all together in alternative embodiments. Although notspecifically shown on the flowchart of FIG. 1, various visual andautomated inspections may be made during the above-described fabricationof the plurality of integrated circuits 102 on panel 100.

Once the plurality of integrated circuits 102 have been formed on panel100, each of the integrated circuits 102 may be encapsulated with amolding compound 120 in step 62 and as shown in FIGS. 3 and 4. Moldingcompound 120 may be an epoxy available for example, from Nitto DenkoCorporation, Osaka, Japan. The molding compound may be applied accordingto various processes, including by transfer molding or flood moldingtechniques, to form a unitary encapsulation on panel 100 encompassingall of the integrated circuits 102.

After molding step 62, a marking can be applied to the molding compound120 in step 64. The marking may for example be a logo or otherinformation printed on the surface of the molding compound for eachintegrated circuit 102. The marking may for example indicatemanufacturer and/or type of device. Marking step 64 may be omitted inalternative embodiments of the present invention.

Each of the integrated circuits 102 may then be singulated in step 66.Singulation step 66 involves cutting integrated circuits 102 on panel100 into a plurality of individual integrated circuit packages. As usedherein, the term “cutting” is used to refer to cutting, sawing, punchingor other methods used to separate the integrated circuits 102 intoindividual integrated circuit packages. Known cutting devices include,for example, water jet cutting, laser cutting, water guided lasercutting, dry media cutting, and diamond coated wire. Water jet cuttingmay be the preferred cutting device given its small cutting width (e.g.,50 microns), its ability to shape small features, and its rapid cuttingrate. Water can also be used together with laser cutting to helpcomplement or focus its effects. As is known in the art, the abovecutting methods are able to achieve sophisticated rectilinear and/orcurvilinear shapes of the individualized integrated circuit packages. Afurther description of the cutting of integrated circuits from a paneland the shapes which may be achieved thereby is disclosed in U.S.Publication No. 2004/0259291, entitled, “Method For EfficientlyProducing Removable Peripheral Cards,” which application is assigned tothe owner of the present invention and which application is incorporatedby reference herein in its entirety. It is understood that thesingulated integrated circuits may be formed by other processes thanthat described above in alternative embodiments.

In embodiments of the present invention, each of the integrated circuitsmay be cut from panel 100 into a shape that fits within and conforms tothe shape of lids for a finished memory card as explained in greaterdetail hereinafter. An outline of the cutting shape in one embodiment isshown in dashed lines 118 on the top view of the encapsulated panel inFIG. 4. As can be seen from the enlarged view of FIG. 5, the integratedcircuits 102 are cut from panel 100 so that the one or more die 114 andpassive components 106 are entirely contained and enclosed within eachsingularized package. Such a package may form a system-in-a-package(“SiP”). The package may alternatively form a multi-chip module (“MCM”)configuration, or other arrangement where a complete electronic systemis formed in a single package. Such packages take up considerably lessroom in the finished flash memory card in comparison to prior art flashmemory cards.

An example of an integrated circuit (“IC”) package 126 which may beobtained by the above-described process is shown in FIGS. 6 through 10.FIG. 6 is a top view of an IC package 126 cut from panel 100 andincluding integrated circuit 102 encapsulated within molding compound124 as described above. IC package 126 may include a top surface 132, afirst edge 134, a second edge 136, a third edge 138 and a fourth edge140 around a periphery of the package. FIGS. 7 through 10 are edge viewsof the first through fourth edges, respectively, of package 126. FIG. 11is a view of a bottom surface 142 of IC package 126 showing contactfingers 143 for establishing an electrical connection in the finishedflash memory card between the card and a host electronic device. WhereIC package 126 is used in an SD Card, IC package 126 may be built as aland grid array (LGA) package. Other types of packages, such as pin gridarray (PGA) and ball grid array (BGA) packages are contemplated.

A chamfer 144 is formed in a corner between first edge 134 and fourthedge 140 for conforming to a chamfer in a flash memory card lid asexplained in greater detail below. A notch 146 may be formed in a cornerbetween second edge 136 and third edge 138 for location of a switch in aflash memory card lid as explained in greater detail below.

Referring again to the flowchart of FIG. 1 and the views of FIGS. 12-14,a completed IC package 126 may further be enclosed within an externalpackage or lid (or pair of lids) 150 in step 68. Such a lid wouldprovide an external covering for the IC package 126 and establishexternal product features. For example, as indicated above, IC package126 may be shaped for use within an SD Card 152 having a standard SDCard lid configuration and footprint. In such an embodiment, the lid 150includes a chamfer 154 between a first pair of edges to prevent the cardfrom being improperly inserted into a standard SD card slot on a hostdevice. In particular, each card slot would include an angled cornerwhich mates with chamfer 154 when card 152 is properly inserted, butwould prevent the card 152 from being fully inserted if some othercorner of the card 152 was inserted against the angled corner within thehost slot.

As indicated above, IC package 126 includes the chamfer 144. The ICpackage 126 is cut so that chamfer 144 matches up with and conforms tothe size and shape of chamfer 154. Similarly, standard SD cards areformed with a switch 156 which cooperates with mechanisms in the hostdevice to enable and disable read/write operations from/to the card. TheIC package 126 is cut so that the notch 146 in package 126 is sized andpositioned to not interfere with the switch 156 as it moves between itsenable and disable positions.

Additionally, forming all of the IC components within package 126provides a significant savings of space within the lids 150 incomparison to conventional printed circuit boards including individuallypackaged components. Whereas the printed circuit board with individuallypackaged components took up all or substantially all of the availablespace within a standard SD Card, the IC package 126 occupies only afraction of the available space. In an embodiment, IC package 126 mayhave a maximum length (between the second edge 136 and fourth edge 140)of approximately 2 cm, and a maximum width (between the first edge 134and third edge 138) of approximately 1 cm. With these dimensions, the ICpackage takes up less than one-half of the available space in card 152.It is understood that the IC package 126 may occupy more than one-halfof the available space within card 152, such as for examplethree-fourths of the available space in card 152.

Embodiments of the present invention have been described including an ICpackage which fits within the footprint of a standard SD card. However,it is understood that embodiments of the present invention mayalternatively shape an SiP, MCM, or other arrangement where a completeelectronic system is formed in a single package to fit within an outerlid or enclosure in a number of other flash memory standards. Suchstandards include but are not limited to a Compact Flash, a Smart Media,a Mini SD Card, an MMC, an xD Card, a Transflash or a Memory Stick.Other devices are contemplated.

The foregoing detailed description of the invention has been presentedfor purposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed. Manymodifications and variations are possible in light of the aboveteaching. The described embodiments were chosen in order to best explainthe principles of the invention and its practical application to therebyenable others skilled in the art to best utilize the invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto.

1. A flash memory card, comprising: an integrated circuit packageincluding a complete electronic system encapsulated in molding compoundto form a single package, the integrated circuit package having first,second, third and fourth edges, a width between the first and thirdedges of approximately one centimeter and a length between the secondand fourth edges of approximately two centimeters, the integratedcircuit package cut with a chamfer between the first and fourth edgesand a notch in a corner where the second and third edges come together;one or more lids for encasing the integrated circuit package, the lidshaving a configuration for a standard SD Card, the chamfer of theintegrated circuit package conforming to the shape of a chamfer formedin the one or more lids, and the notch of the integrated circuit packagedefining a space between the one or more lids in which a switch in theflash memory card travels without contacting the second edge or thethird edge of the integrated circuit package.
 2. A flash memory card asrecited in claim 1, the integrated circuit package cut to include achamfer cut to conform to a shape of a chamfer in the one or more lids.3. A flash memory card as recited in claim 1, the integrated circuitpackage cut to include a notch defining a space in which a switch in theSD Card may operate.
 4. A flash memory card as recited in claim 1, theintegrated circuit package being a system-in-a-package.
 5. A flashmemory card as recited in claim 1, wherein at least one of the first,second, third and fourth sides of the integrated circuit package are cutto a shape to conform to a shape of the one or more lids.
 6. A flashmemory card as recited in claim 1, wherein the one or more lids aretranslucent, the integrated circuit package being visible through theone or more lids.
 7. A flash memory card as recited in claim 1, the cardforming a complete electronic system.
 8. A flash memory card as recitedin claim 1, the single package being a system-in-a-package.
 9. A flashmemory card as recited in claim 1, wherein three sides of the singlepackage are cut to a shape to conform to a shape of the one or morelids.
 10. A flash memory card as recited in claim 1, the integratedcircuit package occupying less than three-fourths of the area of the oneor more lids.
 11. A flash memory card as recited in claim 1, theintegrated circuit package occupying less than one-half of the area ofthe one or more lids.
 12. A flash memory card as recited in claim 1, theintegrated circuit package being a multi-chip module.